/*
 * Licensed to the Apache Software Foundation (ASF) under one
 * or more contributor license agreements.  See the NOTICE file
 * distributed with this work for additional information
 * regarding copyright ownership.  The ASF licenses this file
 * to you under the Apache License, Version 2.0 (the
 * "License"); you may not use this file except in compliance
 * with the License.  You may obtain a copy of the License at
 *
 *     http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package org.apache.flink.runtime.rest.handler.job.checkpoints;

import org.apache.flink.api.common.time.Time;
import org.apache.flink.runtime.checkpoint.CheckpointRetentionPolicy;
import org.apache.flink.runtime.executiongraph.AccessExecutionGraph;
import org.apache.flink.runtime.jobgraph.tasks.CheckpointCoordinatorConfiguration;
import org.apache.flink.runtime.rest.handler.HandlerRequest;
import org.apache.flink.runtime.rest.handler.RestHandlerException;
import org.apache.flink.runtime.rest.handler.job.AbstractAccessExecutionGraphHandler;
import org.apache.flink.runtime.rest.handler.legacy.ExecutionGraphCache;
import org.apache.flink.runtime.rest.messages.EmptyRequestBody;
import org.apache.flink.runtime.rest.messages.ErrorResponseBody;
import org.apache.flink.runtime.rest.messages.JobIDPathParameter;
import org.apache.flink.runtime.rest.messages.JobMessageParameters;
import org.apache.flink.runtime.rest.messages.MessageHeaders;
import org.apache.flink.runtime.rest.messages.ResponseBody;
import org.apache.flink.runtime.rest.messages.checkpoints.CheckpointConfigHeaders;
import org.apache.flink.runtime.rest.messages.checkpoints.CheckpointConfigInfo;
import org.apache.flink.runtime.webmonitor.RestfulGateway;
import org.apache.flink.runtime.webmonitor.history.ArchivedJson;
import org.apache.flink.runtime.webmonitor.history.OnlyExecutionGraphJsonArchivist;
import org.apache.flink.runtime.webmonitor.retriever.GatewayRetriever;

import org.apache.flink.shaded.netty4.io.netty.handler.codec.http.HttpResponseStatus;

import java.io.IOException;
import java.util.Collection;
import java.util.Collections;
import java.util.Map;
import java.util.concurrent.Executor;

/** Handler which serves the checkpoint configuration. */
public class CheckpointConfigHandler
        extends AbstractAccessExecutionGraphHandler<CheckpointConfigInfo, JobMessageParameters>
        implements OnlyExecutionGraphJsonArchivist {

    public CheckpointConfigHandler(
            GatewayRetriever<? extends RestfulGateway> leaderRetriever,
            Time timeout,
            Map<String, String> responseHeaders,
            MessageHeaders<EmptyRequestBody, CheckpointConfigInfo, JobMessageParameters>
                    messageHeaders,
            ExecutionGraphCache executionGraphCache,
            Executor executor) {
        super(
                leaderRetriever,
                timeout,
                responseHeaders,
                messageHeaders,
                executionGraphCache,
                executor);
    }

    @Override
    protected CheckpointConfigInfo handleRequest(
            HandlerRequest<EmptyRequestBody> request, AccessExecutionGraph executionGraph)
            throws RestHandlerException {
        return createCheckpointConfigInfo(executionGraph);
    }

    @Override
    public Collection<ArchivedJson> archiveJsonWithPath(AccessExecutionGraph graph)
            throws IOException {
        ResponseBody response;
        try {
            response = createCheckpointConfigInfo(graph);
        } catch (RestHandlerException rhe) {
            response = new ErrorResponseBody(rhe.getMessage());
        }
        String path =
                CheckpointConfigHeaders.getInstance()
                        .getTargetRestEndpointURL()
                        .replace(':' + JobIDPathParameter.KEY, graph.getJobID().toString());
        return Collections.singletonList(new ArchivedJson(path, response));
    }

    private static CheckpointConfigInfo createCheckpointConfigInfo(
            AccessExecutionGraph executionGraph) throws RestHandlerException {
        final CheckpointCoordinatorConfiguration checkpointCoordinatorConfiguration =
                executionGraph.getCheckpointCoordinatorConfiguration();

        if (checkpointCoordinatorConfiguration == null) {
            throw new RestHandlerException(
                    "Checkpointing is not enabled for this job ("
                            + executionGraph.getJobID()
                            + ").",
                    HttpResponseStatus.NOT_FOUND,
                    RestHandlerException.LoggingBehavior.IGNORE);
        } else {
            CheckpointRetentionPolicy retentionPolicy =
                    checkpointCoordinatorConfiguration.getCheckpointRetentionPolicy();

            CheckpointConfigInfo.ExternalizedCheckpointInfo externalizedCheckpointInfo =
                    new CheckpointConfigInfo.ExternalizedCheckpointInfo(
                            retentionPolicy
                                    != CheckpointRetentionPolicy.NEVER_RETAIN_AFTER_TERMINATION,
                            retentionPolicy != CheckpointRetentionPolicy.RETAIN_ON_CANCELLATION);

            String stateBackendName = executionGraph.getStateBackendName().orElse(null);
            String checkpointStorageName = executionGraph.getCheckpointStorageName().orElse(null);

            return new CheckpointConfigInfo(
                    checkpointCoordinatorConfiguration.isExactlyOnce()
                            ? CheckpointConfigInfo.ProcessingMode.EXACTLY_ONCE
                            : CheckpointConfigInfo.ProcessingMode.AT_LEAST_ONCE,
                    checkpointCoordinatorConfiguration.getCheckpointInterval(),
                    checkpointCoordinatorConfiguration.getCheckpointTimeout(),
                    checkpointCoordinatorConfiguration.getMinPauseBetweenCheckpoints(),
                    checkpointCoordinatorConfiguration.getMaxConcurrentCheckpoints(),
                    externalizedCheckpointInfo,
                    stateBackendName,
                    checkpointStorageName,
                    checkpointCoordinatorConfiguration.isUnalignedCheckpointsEnabled(),
                    checkpointCoordinatorConfiguration.getTolerableCheckpointFailureNumber(),
                    checkpointCoordinatorConfiguration.getAlignedCheckpointTimeout(),
                    checkpointCoordinatorConfiguration.isEnableCheckpointsAfterTasksFinish());
        }
    }
}
